The disclosures contained herein relate generally to energy-storage devices and in particular relate to increasing energy-storage device electrode core operational performance characteristics.
Energy-storage device element design is driven by a variety of parameters, such as, for example, thermal characteristics and electromagnetic problems (e.g., equivalent series resistance (ESR), inductance). One of the most important elements of an energy storage device for optimal functioning is an electrode core. Key operational performance characteristics for the electrode core of an energy-storage device (e.g., ultracapacitor, battery, hybrid energy-storage device, etc.) include, inter alia, thermal control and inductance effects.
A need exists to increase thermal performance of energy-storage device elements, particularly within the electrode core. Also, design enhancements are needed in the area of thermal gradients within the energy-storage device cell and cell-packs (multi-cell modules). Moreover, control of heat flow away from the electrode core is becoming more important, particularly as industry needs, such as electric automobiles, drives the commercial sector. Any advancement in the efficiency of thermal performance will increase the utility of an associated energy storage device. As industry usage of energy-storage cell modules increases (such as, for example, in “hybrid” automobiles), the need to control thermal gradients in such modules is fast becoming evident. In addition, usage of such cell modules in geographical regions which have relatively high ambient temperatures, would greatly, benefit from a better energy-storage device design emphasizing thermal considerations.
Another design issue with some energy-storage devices, such as modern ultracapacitor cells, is internal inductance, generated by the circumferential current flow about the “jelly-roll” inside the cell core. Such an inductance creates an undesirable impedance for an ultracapacitor electrode core, ultimately degrading performance, as will be appreciated by those of skill in the art. Any reduction in the amount of internal inductance within the electrode core would improve performance.
Moreover, as will be appreciated by those of ordinary skill in the energy-storage device electrode core arts, inductance of ultracapacitor electrode cores causes damage to cell-module balancers, due to over-voltage. Therefore, a need exists for a reduction in failure of energy-storage device cell modules due to balancer damage.
Furthermore, modern cell construction techniques for ultracapacitors includes a core involute. The core involute contributes to sharp bend radii of an electrode core (contributing to “hot” spots in the electrode core), and possibly contributes to leakage current. Such hot spots and leakage current further degrade ultracapacitor performance.
Therefore, a need exists to improve the thermal and electromagnetic performance of an energy storage device electrode core, as well as reducing problematic effects of a core involute.